#include "mystdio.h"


myFILE* my_fopen(const char *path, const char *flag)
{
    int flag1 = 0;
    int iscreate = 0;
    mode_t mode = 0666;
    if(strcmp(flag, "r") == 0)
    {
        flag1 = (O_RDONLY);
    }
    else if(strcmp(flag, "w") == 0)
    {
        flag1 = (O_WRONLY | O_CREAT | O_TRUNC);
        iscreate = 1;
    }
    else if(strcmp(flag, "a") == 0)
    {
        flag1 = (O_WRONLY | O_CREAT | O_APPEND);
        iscreate = 1;
    }
    else
    {}

    int fd = 0;
    if(iscreate)
        fd = open(path, flag1, mode);
    else
        fd = open(path, flag1);

    if(fd < 0) return NULL;

    myFILE *fp = (myFILE*)malloc(sizeof(myFILE));
    if(!fp) return NULL;

    fp->fileno = fd;
    fp->flags = FLUSH_LINE;

    fp->cap = LINE_SIZE;
    fp->pos = 0;

    return fp;
}

void my_fflush(myFILE *fp)
{
    write(fp->fileno, fp->cache, fp->pos);
    fp->pos = 0;
}

ssize_t my_fwrite(myFILE *fp, const char *data, int len)
{
    // 写入操作本质是拷贝, 如果条件允许，就刷新，否则不做刷新
    memcpy(fp->cache+fp->pos, data, len); //肯定要考虑越界, 自动扩容
    fp->pos += len;

    if((fp->flags&FLUSH_LINE) && fp->cache[fp->pos-1] == '\n')
    {
        my_fflush(fp);
    }

    return len;
}

void my_fclose(myFILE *fp)
{
    my_fflush(fp);
    close(fp->fileno);
    free(fp);
}
  

